1. Technical Field
The present disclosure relates to a method for making magnesium-based composite material.
2. Description of Related Art
Nowadays, various alloys have been developed for special applications. Among these alloys, magnesium alloys have relatively superior mechanical properties, such as low density, good wear resistance, and high elastic modulus. However, the toughness and the strength of the magnesium alloys are not able to meet the increasing needs of the automotive and aerospace industry for tougher and stronger alloys.
To address the above-described problems, magnesium-based composite materials have been developed. In the magnesium-based composite material, nanoscale reinforcements (e.g. carbon nanotubes and carbon nanofibers) are mixed with the magnesium material or alloy. The nanoscale reinforcements can be carbon nanotubes, silicon carbide, aluminum oxide, titanium carbide, or boron carbide.
In an article entitled, “Mechanical properties and microstructure of SiC-reinforced Mg-(2,4)Al-1Si nanocomposites fabricated by ultrasonic cavitation based solidification processing” by G. Gao, et al., Materials Science and Engineering A, 486, 357-362 (2008), a method for making magnesium-based composite material is disclosed. The method comprises the following steps: providing a liquid-state Mg—(2,4)Al-1Si alloy of 800 grams at a temperature of 700° C.; dipping a ultrasonic probe into the liquid-state Mg-(2,4)Al-1Si alloy for about 25 millimeters to about 31 millimeters in depth and ultrasonically processing the alloy at 700° C. Feeding silicon carbide nanoscale powders into the alloy during the ultrasonic processing to obtain a magnesium-based composite material in which the weight percentage of the silicon carbide nanoscale powders is 2 wt %. Performing the ultrasonic process for about 15 minutes and increasing the temperature of the magnesium-based composite material to 725° C. at the same time. Pouring the magnesium-based composite material into a mold. However, using the above-described method, the silicon carbide nanoscale powders are dispersed only by ultrasonically processing. Because a density of the silicon carbide nanoscale powders is very small, the silicon carbide nanoscale powders trend to stay on a surface of the liquid-state alloy and are not easily dispersed uniformly into the whole magnesium-based composite material.
What is needed, therefore, is to provide a method for making a magnesium-based composite material in which the nanoscale reinforcements are dispersed uniformly.